ABSTRACT
This chapter starts by discussing the composition of atmospheric air followed by a description of the important moist-air thermodynamic properties. Next, we present tabulated data and analytical equations to determine psychrometric properties of moist air common in air-conditioning processes. Important processes involving mixing of streams, cooling/heating, and humidification/dehumidification are then discussed in detail. All the analytical and design information in this chapter is based on the application of the first law of thermodynamics and the conservation of mass along with state properties of air and water vapor. Finally, we discuss the construction and use of the psychrometric chart, an essential tool to HVAC designers. A sound mastery of the material in this chapter is essential for proper comprehension and analysis of how secondary HVAC systems are designed and operated. Students who may have been previously exposed to psychrometrics during their thermodynamics course are urged to review this chapter.
